This invention relates to a reclosable bag that has a gusset structure which provides a base when filled for supporting the reclosable bag in an upright position. This invention further relates to a reclosable bag which has a tamper evident seal over the reclosable fastener.
There is a need for reclosable bags for products that are used in partial amounts and which need to be isolated from the atmosphere after the bag is opened. A usable resealable unit is a zipper-type of seal where the bag can be opened and reclosed. The bags usually will have a permanent seal above the zipper-type of seal that serves to secure the bag until it is opened. This permanent seal can be an extension of the front wall and rear wall that is sealed together above the zipper-type seal. In order to open such a bag the front and rear wall is cut above the zipper-type seal and removed to expose the zipper-type seal. Also, there may be a perforation above the zipper-type seal to assist in removing part or all of the front or rear wall to expose the zipper-type reclosable seal.
The prior art for bags with zipper-type of seals is set out in U.S. Pat. No. 5,833,791, U.S. Pat. No. 5,919,535 and PCT Application WO98/24339. U.S. Pat. No. 5,833,791 discloses a zipper-type of seal with a particular end stop to keep the zipper from sliding off the track. These end stops must be of a strength so as to secure the slides throughout the period of use. U.S. Pat. No. 5,919,535 discloses a bag with a zipper-type of seal where each of the zipper-type lock segments have fin pieces which attach to the front and rear walls of the bag. PCT Application WO98/24339 discloses a zipper-type of seal with a perforated area above the zipper-type seal to facilitate opening of the bag. The slide zipper seal is maintained in a closed position until part of the front and/or rear wall is removed to expose the primary slide zipper seal for the opening of the bag.
These bags and the resealable closures are very useful. However, other features are necessary in various bags. These include features to make the bags easier to fill, close after filling, and stack for shipping, storage and display at the point of sale. The present invention is directed to reclosable bags that are easily and quickly filled, can be vented, and have improved storage and handling features.
The invention comprises a reclosable bag that has a slide zipper reclosable seal at one end. The bag is comprised of a front wall and a rear wall with two sidewalls connecting the front wall to the rear wall. Each sidewall has a gusset structure. The upper end of the bag is closed with a reclosable slide zipper seal and in a first embodiment with the front and rear wall extending above the reclosable slide zipper seal and attached to each other above this seal to enclose the reclosable slide zipper seal. In a further embodiment the slide zipper reclosable seal may be at the top edge of the bag. The bag is open at the bottom for bottom filling and after bottom filling is sealed.
In the first embodiment where the front and/or rear wall extends above the reclosable slide zipper seal there can have a perforation extending essentially parallel to the slide zipper seal to facilitate the opening of the enclosure of the slide zipper seal. This enclosure functions as a tamper-evident seal for the primary zipper-type seal since it must be removed in order to open the bag.
In the further embodiment the slide zipper reclosable seal is attached to a top edge of the bag with the tamper evidency formed within the bag by a loop of film attached to each side of the zipper. This loop of film must be severed in order to open the bag and remove any of the contents.
The bag has a narrowed opening at the bottom to assist in the filling of the bag. At the bottom edge the end portions are bonded together to form this narrowed opening. This is a bonding of the front and rear walls through the sidewall gussets. This bonding is enhanced by apertures in at least one of the gusset walls so that there is a bonding of a bonding layer of a film to another film surface. And in a further preferred embodiment the inwardly folded gussets are tack welded to either the front or rear wall so that they do not interfere with the insertion of a filling tube into the bag.
In a preferred embodiment the reclosable bag has a seal adjacent to each corner of the reclosable bag. These seals reduce the volume of the bag and at the bottom of the reclosable bag enhance the gusset sidewall self-supporting feature and at the upper portion of the reclosable bag keep product from the ends of the slide zipper seals, but have at least one passage therethrough for venting the bag. In a yet further preferred embodiment these seals are generally diagonal seals at the corners.
Adjacent the upper end the bag there is at least one vent so as to equalize the air pressure in the bag and the external air pressure such as when the filled bags are being stacked on pallets for shipping. This at least one vent is formed by at least one small opening adjacent the slide zipper seal. The upper corner seals prevent product from accumulating at a vent and to minimize liquids wicking through the vents.
The reclosable bag is made by unwinding a film, usually a rear wall film, bondable side facing up. Preformed gusset tubes with a bondable exterior surface are attached to this film in a cross direction. A preformed reclosable slide zipper seal is bonded to the this film and attached gusset tubes at an upper portion thereof and a another film, usually the front wall film, bondable side facing downward is attached to the slide zipper reclosable seal and to the gusset sidewalls. In a further step, seals are formed adjacent the corners of the reclosable bag decreasing the volume of the bag, the seals at an end of the bag adjacent the reclosable slide zipper seal having a at least one passage therethrough for venting of the reclosable bag. The reclosable bag has a vent opening to the bag exterior adjacent the ends of the reclosable slide zipper seal to equilibrate the pressure in the bag with the exterior pressure. A prime advantage is when the bags are compressed when stacked in a pallet. Unvented bags will form unstable stacks.
When the bag is to have the tamper evident structure of the first embodiment, both films, that is the rear wall film and the front wall film, are each in a first step perforated above the slide zipper reclosable seal and the films sealed together at an upper edge. When the tamper evident structure is of the further embodiment, neither film is perforated and the slide zipper reclosable seal is bonded to the top of the top edge of these films which comprise the front and rear walls.
The bag in a first embodiment is opened by severing the perforations in the area above the slide zipper seal to expose the slide zipper seal which is the primary seal. The zipper then is opened and product removed. The bag is resealed after removing a portion of the product by closing the slide zipper seal. In the further embodiment the bag is opened by opening the zipper and then severing a film seal that extends downward into the bag from the slide zipper seal.